From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Morris Subject: Re: [RFC PATCH v1 0/5] Add support for O_MAYEXEC Date: Thu, 13 Dec 2018 10:40:32 +1100 (AEDT) Message-ID: References: <20181212081712.32347-1-mic@digikod.net> <87lg4upkpv.fsf@oldenburg2.str.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: <87lg4upkpv.fsf@oldenburg2.str.redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Florian Weimer Cc: =?ISO-8859-15?Q?Micka=EBl_Sala=FCn?= , linux-kernel@vger.kernel.org, Al Viro , Jonathan Corbet , Kees Cook , Matthew Garrett , Michael Kerrisk , =?ISO-8859-15?Q?Micka=EBl_Sala=FCn?= , Mimi Zohar , =?ISO-8859-15?Q?Philippe_Tr=E9buchet?= , Shuah Khan , Thibaut Sautereau , Vincent Strubel , Yves-Alexis Perez , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org List-Id: linux-api@vger.kernel.org On Wed, 12 Dec 2018, Florian Weimer wrote: > * James Morris: > > > If you're depending on the script interpreter to flag that the user may > > execute code, this seems to be equivalent in security terms to depending > > on the user. e.g. what if the user uses ptrace and clears O_MAYEXEC? > > The argument I've heard is this: Using ptrace (and adding the +x > attribute) are auditable events. I guess you could also preload a modified libc which strips the flag. -- James Morris